Because they pollinate crops near their hives, wild and feral bees are assets to farmers. Ecologists recognize such pollination as one benefit of conserving wooded habitat adjacent to farmland (SN: 7/6/02, p. 13).

Now, scientists working in Costa Rica suggest that a square kilometer of tropical forest can be worth $40,000 or more per year to neighboring coffee plantations. That's on par with the potential value of using the land for other purposes, such as grazing cattle, the scientists say.

The research team, led by Taylor Ricketts of Stanford University, examined the productivity of coffee plants in different areas of a plantation that covers nearly 11 [km.sup.2.] Although the plants can grow without insect pollinators, they produce more and consistently larger berries when visited by forest-dwelling bees.

Plants growing close to a forest are about 20 percent more productive than plants growing a kilometer or more away, the scientists report in an upcoming Proceedings of the National Academy of Sciences. That benefit translates into a boost of more than $60,000 to the plantation's annual income from fragments of forest covering barely 1.5 [km.sup.2]. The woods probably also improve productivity on neighboring coffee farms, the scientists add.--B.H.

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